Re: [PATCH bpf-next v3 2/3] bpf: Use bpf_core_enum_value for stats in cgroup_iter_memcg

[Emil Tsalapatis]

On Sat Feb 28, 2026 at 2:11 AM EST, Hui Zhu wrote:
> From: Hui Zhu <zhuhui@xxxxxxxxxx>
>
> Replace hardcoded enum values with bpf_core_enum_value() calls in
> cgroup_iter_memcg test to improve portability across different
> kernel versions.
>
> The change adds runtime enum value resolution for:
> - node_stat_item: NR_ANON_MAPPED, NR_SHMEM, NR_FILE_PAGES,
>   NR_FILE_MAPPED
> - memcg_stat_item: MEMCG_KMEM
> - vm_event_item: PGFAULT
>
> This ensures the BPF program can adapt to enum value changes
> between kernel versions.
>
> Signed-off-by: Hui Zhu <zhuhui@xxxxxxxxxx>

Bot's comments aside:

Reviewed-by: Emil Tsalapatis <emil@xxxxxxxxxxxxxxx>

> ---
>  .../selftests/bpf/progs/cgroup_iter_memcg.c     | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/progs/cgroup_iter_memcg.c b/tools/testing/selftests/bpf/progs/cgroup_iter_memcg.c
> index 12f79a44133e..06a385c9d85b 100644
> --- a/tools/testing/selftests/bpf/progs/cgroup_iter_memcg.c
> +++ b/tools/testing/selftests/bpf/progs/cgroup_iter_memcg.c
> @@ -26,11 +26,18 @@ int cgroup_memcg_query(struct bpf_iter__cgroup *ctx)
>  
>  	bpf_mem_cgroup_flush_stats(memcg);
>  
> -	memcg_query.nr_anon_mapped = bpf_mem_cgroup_page_state(memcg, NR_ANON_MAPPED);
> -	memcg_query.nr_shmem = bpf_mem_cgroup_page_state(memcg, NR_SHMEM);
> -	memcg_query.nr_file_pages = bpf_mem_cgroup_page_state(memcg, NR_FILE_PAGES);
> -	memcg_query.nr_file_mapped = bpf_mem_cgroup_page_state(memcg, NR_FILE_MAPPED);
> -	memcg_query.pgfault = bpf_mem_cgroup_vm_events(memcg, PGFAULT);
> +	memcg_query.nr_anon_mapped = bpf_mem_cgroup_page_state(
> +		memcg,
> +		bpf_core_enum_value(enum node_stat_item, NR_ANON_MAPPED));
> +	memcg_query.nr_shmem = bpf_mem_cgroup_page_state(
> +		memcg, bpf_core_enum_value(enum node_stat_item, NR_SHMEM));
> +	memcg_query.nr_file_pages = bpf_mem_cgroup_page_state(
> +		memcg, bpf_core_enum_value(enum node_stat_item, NR_FILE_PAGES));
> +	memcg_query.nr_file_mapped = bpf_mem_cgroup_page_state(
> +		memcg,
> +		bpf_core_enum_value(enum node_stat_item, NR_FILE_MAPPED));
> +	memcg_query.pgfault = bpf_mem_cgroup_vm_events(
> +		memcg, bpf_core_enum_value(enum vm_event_item, PGFAULT));
>  
>  	bpf_put_mem_cgroup(memcg);
>